In a brief outpatient procedure, a corneal specialist implants the mini-telescope in one eye in place of its natural lens. The telescope magnifies images on the retina, extending them so they fall on healthy cells outside the damaged macula, said Allen W. Hill, chief executive of VisionCare Ophthalmic Technologies in Saratoga, Calif., the implant's maker.

The telescope is implanted in one eye for jobs like reading and facial recognition. The other eye, unaltered, is used for peripheral vision during other activities like walking.